1. Field of the Invention
The present invention relates to a dispensing can for viscous substances.
2. Description of the Prior Art
At present, dispensing cans for viscous substances usually have a can body in which there is a container of viscous substances made of a semi-rigid material such as aluminium sheeting. The container of viscous substances is connected to a dispensing head and the body of the container is filled with a gas under pressure. The opening of a dispensing valve causes the viscous substance to be expelled outside the can and this substance to be dispensed under the pressure of gas on the semi-rigid wall of the container.
These cans have several drawbacks. These include, for example, the necessarily incomplete deformation of the container made of a semi-rigid material, especially its bottom. The consequence of this incomplete deformation is a substantial loss of viscous substance as it cannot be expelled from a partially deformed container.
Besides normally, and especially when the viscous substance is a medicinal or viscous product, the container and the can body should be coated with a protective varnish. In certain cases, it has been observed that the stability of these varnishes is inadequate for certain substances, resulting in corrosion in the materials that form the body of the can and/or the container, the consequence of which is considerable reduction in preservation and storage times for these substances packaged in this way. The risk of non-functioning of these cans most usually results from the gradual leakage of gas and from the absence of pressure during the use of these cans or from defective dispensing heads. These risks are hardly tolerable when medicinal substances have to be dispensed during swift operation such as, for example, in the case of burns.
Furthermore, in view of the nature of the pressurized gas used, it is not easy to refill these cans with viscous substances and, consequently, their proliferation as consumer objects to be discarded after use creates a considerable problem of rational disposal with a view to avoiding pollution risks. The risk of explosion of these cans, when they are subjected to temperatures of more than 50.degree. C., is also considerable.